1. Field of the Invention
The invention relates to flue gas desulfurization apparatuses for absorbing sulfur oxides in flue gases and cleaning up the flue gases.
2. Description of the Related Art
Conventionally, a flue gas desulfurization apparatus has been proposed, for example, for flue gas treatment in thermal power plants and the like. An example of the conventional flue gas desulfurization apparatuses is shown in FIG. 13.
As shown in FIG. 13, a flue gas desulfurization apparatus 100 includes an inlet-side absorption tower 102 having an opening 102a in an upper portion for taking in an untreated flue gas 101, an outlet-side absorption tower 104 having an opening 104b in an upper portion for discharging a treated purified gas 103, and the inlet-side absorption tower 102 and the outlet-side absorption tower 103 are arranged next to each other. In each of the absorption towers 102 and 104, plural spray pipes 106 are arrange parallel to each other in a horizontal direction. The spray pipe 106 has plural nozzles 105 disposed at predetermined intervals. Each spray pipe 106 is connected to a circulation pump 108 which supplies absorption slurry 107 to the spray pipe 106.
The flue gas 101 introduced into the inlet-side absorption tower 102 from the opening 102a flows downward, passes through a space 110 in a reservoir 109 which communicates the inlet-side absorption tower 102 and the outlet-side absorption tower 104 with each other, and thereby moves from the inlet-side absorption tower 102 to the outlet-side absorption tower 104. Thereafter, the flue gas 101 flows inside the outlet-side absorption tower 104 upward. When the absorption slurry 107 is ejected upward from each of the nozzles 105 like a liquid column while the flue gas 101 moves through the absorption tower 102 downward and through the absorption tower 104 upward, the liquid-column-like absorption slurry 107 is brought into contact with the flue gas 101, thereby absorbing sulfur oxides contained in the flue gas 101. The treated purified gas 103 passes through an exhaust passage 104a in the outlet-side absorption tower 104 and is discharged from the opening 104b. The absorption slurry 107 is processed into plaster or the like in a separate sulfate treatment facility 113 (see, for example, Japanese Patent Application Laid-Open No. 2006-255629).
On the outlet side of the outlet-side absorption tower 104 of the flue gas desulfurization apparatus 100, mist eliminators 112A and 112B are disposed as shown in FIG. 14 to prevent dispersion of the purified gas 103 and a mist 114. However, a mist of a small particle diameter (for example, a mist of a submicron order not more than a few μm) can pass through the mist eliminators 112A and 112B and disperse.
In addition, since an outlet portion of the outlet-side absorption tower 104 has a bend portion R so that the outlet-side absorption tower 104 can be connected to a stack which discharges the purified gas 103, a drift occurs around the mist eliminators 112A and 112B.
When there is a drift, a gas flow of a flow rate equal to or higher than a limit flow rate of the mist eliminators 112A and 112B can be generated locally (particularly at the side of an inside corner) to make the mist 114 disperse.
Particularly when the opening 104b connected to the stack side has a small section area, an amount of the drift increases.